question about doubler

I own a sony A-200 my shots an A-100 but also have quite a few lenses from an old minolta that both me and my wife used to use. I tried using our Tamron doubler on both one of our sony lenses and an older Tamron lense. For some reason it doesn't like the new sony camera. However if I use our 1.4 it works fine. Any ideas?

Could it be that you can't auto focus with the 2X teleconverter? If so, that's easy to explain. A teleconverter steals some light a 2X takes away about two stops. Most cameras need a minimum of F5.6 in order to auto focus...so unless your max is F2.8 or larger, the loss of two stops will put you past the F5.6 that you need...therefore, you won't have enough light for AF.

Being into photography for only about a year or so when I say that it doesn't like the new camera, it sounds like the autofocus on the lenses just keeps going and going all I hear is a whirring and clicking. With the 1.4 eveything works normally. I even tried switching off the autofocus and it still does it.